So the previous owner of this place (a flipper) installed crapass Closet Maid wire shelves in the closets. I've had two collapse now, so I've decided to replace them with simple 3/4" plywood shelves on top of 1x4 all around with metal supports in the middle and proper wooden hanger rods.

Uuuuunfortunately, I've just run into a hitch. I have a rather iffy studfinder, but what I've discovered with it (and by putting a big enough hole into the drywall to shine a light in) is that the closet is built with metal studs. Any tips on how to deal with this? I have no desire to replace the studs in the closet, but I'm not sure what kind of screws to use to secure the 1x4s and supports or whether what I want to do is even feasible.

For reference, I'm doing something like this. And yes, I've already bought the plywood and the lumber, although I haven't cut it to exact size yet.